The Parties' Contentions

The Judge summarised the parties' respective positions as follows:"4. The case brought on DS's behalf alleges that there was negligent delay at the end of his mother's labour in that the midwives failed to realise that his heartbeat had dropped to dangerous depths until 1500 hours; that this was because inadequate monitoring was being carried out: that once they discovered this the labour should have been managed in such a way that medical assistance was called for minutes before it was and that the doctor who then arrived should have made the decision to deliver by emergency caesarean section at least a couple of minutes before she did. But for the negligent delay DS's delivery would have been achieved 6 or 9 minutes before 1529 hours and the saving of time would have been sufficient to reduce the effects of the period of damaging hypoxia to a materially less damaging injury."5. The Trust defends the claim on both negligence and causation. It denies that its midwives or doctor acted in breach of their duties or that they delayed any appropriate and reasonable step in FS's care. Also medical causation cannot be established because on the balance of probabilities even an interval of ischaemic hypoxia shorter by 6-9 minutes that than which DS sustained would have caused essentially the same injury and the only way to avoid it would have been for DS to have been delivered within 10 minutes of the hypoxia starting."

Causation

The Judge found against the Claimant on its primary case on breach of duty but went on to consider issues of causation:"150. Given the findings I have made as to negligence, namely that there was a maximum of 3 minutes of negligent delay from 1504 to 1507 only, the evidence of the remaining experts, particularly those concerned with causation, is strictly of less relevance, as it has not been contended that a saving of 3 minutes would have materially affected the degree of injury. However, lest my findings on breach of duty are challenged subsequently I will go on to consider the case on causation both on the basis of a 6-9 minute negligent delay and a 3 minute negligent delay."
After reviewing the expert and other evidence the Judge concluded as follows:"196. On the basis of saving 6-9 minutes of negligent delay:i)It is agreed that DS's motor functions would not be materially different.ii)Although there is understood to be a relationship between the duration of an acute profound hypoxic episode and the severity of brain injury caused, the relationship is not simple to define. The Claimant was apparently a healthy and robust foetus. He suffered a long period of hypoxia, at least 39 minutes (1500-1539) but more probably longer. Making an allowance of the generally accepted 10 minutes of non-harmful hypoxia (as described by the paediatric neurologists), he survived at least 29 minutes of injurious hypoxia but displays less profound injury than might be expected after that period of exposure. His neurological disabilities are atypical and not at the most severe end of the spectrum.iii)While common sense suggests that a reduction of 6-9 minutes of exposure (as a proportion of the whole) would have made a difference to DS's cognitive abilities it is difficult to be certain, whether it would have been a material difference. This is especially so when DS's atypical radiology results are taken into account however, I have to apply a lower threshold of proof, namely the balance of probabilities....vii) I am persuaded that if birth had been as much as 9 minutes earlier, a substantial proportion of the total hypoxic insult would have been avoided and although I cannot calculate it exactly I am satisfied on the balance of probabilities that it would have made a material difference to DS's cognitive abilities so that although the care support he needed may have been the same his ability to manage himself, to make daily (not legal) decisions and the degree to which he would be able to join in his care would have been substantially improved."viii)On the other hand, in all the circumstances the Claimant has not persuaded me that it is likely he would have suffered materially less injury had he been delivered 6 minutes before 1529 on 4th June 2005. DS was bound to suffer significant brain damage from the acute hypoxia following placental abruption until resuscitation and although a saving of 6 minutes before delivery and a consequential shorter period of necessary resuscitation may have made some proportionally minor difference to his cognitive functioning, it is impossible to say to what extent that saving of time would have improved his current condition."

Material Difference or Material Contribution?

The evidence and finding of a period of profound hypoxia ischaemia of at least 39 minutes "but more probably longer" is remarkable and very unusual. However the upshot is that context of the (obiter) causation findings was that 6 to 9 minutes of the, say, 29 minutes of harmful hypoxia ischaemia, were avoidable.The Judge seems to have asked herself the question: has C proved that the "avoidable" period of harmful hypoxia ischaemia made a material difference to the Claimant's cognitive abilities or functioning? She was satisfied that if the avoidable period were 9 minutes, then the answer was "Yes". If the avoidable period were 6 minutes then the answer was "No". The Defendant appears to have contended that if brain damage, however severe, would have been inevitable even absent the negligence, then the Claimant could not recover any compensation: had hypoxia been longer than 10 minutes then essentially the same brain damage injury would have been suffered (see paragraph 5 of the judgment above). The Judge must have rejected that contention. It is true that the first question in the Bailey v MOD test of causation is:"If the evidence demonstrates on a balance of probabilities that the injury would have occurred as a result of the non-tortious cause or causes in any event, the claimant will have failed to establish that the tortious cause contributed".
But there is a difficulty in applying that test to cases of injury caused by a process, some of which is negligent, some non-negligent. Such cases are not, as the Defendant in DS seems to have contended, "all or nothing" in the following sense. In Bailey the injury was a sudden event with more than one, but very distinct, contributory causes. In DS as in Williams v Bermudathere was a process causing injury. In Williams the process was the development of sepsis. The Privy Council held that,"[The] development [of sepsis] and effect on the heart and lungs was a single continuous process, during which the sufficiency of the supply of oxygen to the heart steadily reduced." [41]. On the balance of probabilities the negligent delay, found to be at least 2 hours 20 minutes "materially contributed to the process, and therefore materially contributed to the injury to the heart." [42]."Likewise with cerebral palsy caused by hypoxic ischaemia. There is a continuous process during which the supply of oxygen to the brain is interrupted. Some of that period is "non-harmful" only in the sense that, without more, it would not cause injury; some is harmful and avoidable; some is harmful and unavoidable. The whole period causes the brain injury. The negligent part contributes to the whole.

Assessing Quantum

How would Mrs Justice Cheema-Grubb have assessed quantum on her finding that a "negligent" 9 minute delay made a material difference to the Claimant's cognitive abilities? The alternatives would have been to assess damages for the whole of the injury, because the avoidable 9 minutes made a material contribution, or to assess damages for the additional injury caused by the avoidable 9 minutes. My guess is that the Judge would have sought to assess on the latter basis because the implication of the judgment on causation is that the Judge approached hypoxic ischaemic brain damage at or around the time of birth as a dose-related injury susceptible to a quantifiable attribution of injury to cause.

The judgment is not easy to reconcile with the approach taken in Poppleand, in a closely related case,Johnneither of which were referred to in the judgment. In Popple Ward LJ held that "If [the hypoxic insult] did take 20 minutes, the damage done in the last five minutes must have made a contribution to the overall harm which was more than minimal. I cannot see why the Bailey principle does not apply."
It is perfectly possible for one court to find on the facts that 5 minutes of a 20 minute period of hypoxia is material, and for another to find that 6 minutes of a 29 minute period is not material. Each case must be determined on its own facts. However, the question Ward LJ asked himself appears to have been, "Did the avoidable period of hypoxia make a material contribution to the overall harm?", not, "Did the avoidable period of hypoxia cause material or quantifiable additional harm?"The question of whether a negligent period of hypoxia made a a material contribution to the injury sustained is not necessarily the same question as whether it made a material difference to the outcome?The "material contribution" principle applies precisely in those cases where one cannot quantify the degree of injury attributable to the negligent cause. As was held in the brain injury case of John :"... the Bailey and Williams cases are cases where it was impossible, not merely difficult, to attribute particular causes to particular loss. The present case likewise entails impossibility rather than simply difficulty. As such, it is not an appropriate case for an apportionment exercise." So, the fact that the Claimant cannot prove a quantifiable difference in outcome did not preclude recovery of compensation - indeed the Claimant recovered compensation for the whole of the injury suffered.It is possible that on the facts the Court might find that a period of avoidable hypoxia has not made a material contribution to the overall harm. But that is a different question from the one the Court appears to have asked itself in DS.Popple, Williams and John, seemed to establish that where there are successive causes, negligent and non-negligent, which are part of a process leading to the final injury, and the negligent cause made a material but unquantifiable contribution to that process and to the final injury, then the Defendant is liable to compensate the Claimant for the whole of the injury. DS appears to point another way.

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Learned Friend is the blog of Nigel Poole QC. Nigel practises at Kings Chambers with offices in Manchester, Birmingham and Leeds. He specialises in clinical negligence and personal injury law. These posts are intended to be of general interest and no-one should rely on them as definitive statements of the law. They are no substitute for full advice in any particular case. I would welcome comments on the posts and suggestions for future topics.
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